I really appreciate those suggestions. The Invicta looks amazing and would be my top priority DAC of choice if there were used models on the market! I am concerned about them being a new company, though, re any maintenance/repairs needed for the device.
Have heard good things about Acoustic Arts but never seen any FS... will keep a close eye for that too. Most of the aforementioned DACs are completely new to me (Aesthetix, Ayre, Calyx, M2Tech) and have a lot of reading to do!
I'm going to try my best to stick to my plan of going for the O2 MKII and a lower-end (but adequate) amp, will upgrade my DAC around Christmas, and aim for the BHSE in a year or two. My gf doesn't think I have the self-restraint, though, and will pull the trigger on the BHSE sooner
I've pretty much committed to buying the SR-007 O2 MKII and a GES this week (both mentally and in writing). I will miss my solid-state setup, but when I inevitably return to solid-state, the LCD2 or one of the HEs is at the top of my list (probably paired with a GS-X). I've read mixed things from the technical/DIY crowd on the SR-009s so I'll hopefully have a chance to demo them at the next Bay Area meet, but most people seem to love the SR-007 MKII.
I've heard the KGSS is the logical step down from the BHSE but that's $500-1000 above I want to spend right now, and KGSSes are uncommon on FS forums and get snapped up pretty quick. I read some people who seem credible in the technical crowd who say the GES is competent for the SR-007 MKII as a first electrostat amp, or the SRM-323S or a modded SRM-T1. I can't find any head-to-head comparisons of the SRM-323S vs the GES, but from looking at the specs and price, they seem roughly in the same category so I should hopefully be fine, and the GES (like most Woo gear) has good resaleability and straightforward maintenance and modding potential. I'm not a big Sennheiser fan, so I have my heart set on the Stax.
Most people who are in the budget bracket below the KGSS seem to default to a Stax amp with the SR-007, so I'm interested to hear how everything turns out. Legend has it nothing comes close to the BHSE, but ever since listening to the LCD2s, I'm pretty bothered by the lack of bass and stage every time I listen to my SR225i and now I must upgrade.
Anyway, any suggestions on good DACs to eventually pair with a BHSE and a SR-007 O2 MKII (or any other general setup improvements) are greatly appreciated!